Formation of the Dental Hard Tissues Part 1: Dentinogenesis Flashcards
What are the stages of tooth germ develoment?
What type of tissue is the papilla?
Ectomesenchymal derived from neural crest
what cells form dentine?
odontoblasts derived from neural crest cells.
What is the components of Dentine?
70% Mineral – Hydroxyapatite
20% Organic Matrix:
– Collagen (mainly type I)
– Extracellular Matrix/Ground substance:
- Dentine Phosphoproteins
- Proteoglycans
- Lipids
10% Water
When does dentine formation begin and where does it begin?
Begins at end of bell stage
Starts at cusp tip
What are the 3 stages of dentine formation?
– Cytodifferentiation
– Matrix formation
– Mineralisation
What is the significance of this interface in a tooth?
It is the position of the future amelodentinal junction (ADJ)
What are the 2 different areas?
What are the cells labelled in the bell stage?
What is labelled in the basal lamina?
What happens in the Matrix secretory phase?
Odontoblast secretes the organic matrix: – Pre-dentine
What happens in Initial Mineralisation?
- Matrix vesicles involved
- Crystals grow and aggregate obscuring collagen
- Basal lamina disintegrates
– signals start of enamel formation
During the mineralisation of Dentine what happens Once hydroxyapatite crystals are formed?
hydroxyapatite grows in a spherical form - globular : Calcospherites – these eventually fuse
What is interglubular dentine?
Interglobular Dentine failure of calcospherite fusion.
What are the 2 types of dentine?
Mantle dentine
The 1 st formed dentine adjacent to enamel
characterised by:
– large collagen fibrils at 90 to the ADJ
– MVs
– ground substance not all of Odontoblast origin
– Slightly less mineralised (by ~5%)
Circumpulpal dentine
Rest of the dentine
Ground substance from Odontoblasts
Collagen fibrils
– closely packed + interwoven
– small collagen fibrils parallel to the ADJ
Mineralisation:
– No Matrix vesicles
– heterogeneous nucleation
Label the diagram:
